Method for recycling metal in waste lithium iron phosphate battery based on advanced oxidation and application

Abstract

The invention relates to recycling treatment of waste lithium iron phosphate batteries, and provides a method for recycling metals in waste lithium iron phosphate batteries based on advanced oxidation and application. The type of the waste lithium battery is a soft package type lithium iron phosphate battery, a positive electrode material in the waste lithium iron phosphate battery is obtained through simple discharge and disassembly of an instrument, after grinding, positive electrode material powder and an oxidizing agent are mixed and reacted with water in a reactor according to a certain proportion, lithium ions are released into an aqueous solution, and the lithium ion battery is obtained. Sodium carbonate is added for evaporation and filtration, and lithium is recycled in the form of lithium carbonate. The invention provides a new scheme for selectively recovering lithium in the waste lithium iron phosphate battery, and the scheme has the characteristics of simple recovery process and high efficiency.

Description

Technical Field

[0001] The present invention relates to the recycling of waste lithium iron phosphate batteries, and in particular to a method and application of recycling metals in waste lithium iron phosphate batteries based on advanced oxidation. Background Art

[0002] With the substantial growth in the production of new energy vehicles, the lithium-ion battery industry has developed rapidly and has become one of the most common forms of energy storage. However, with the surge in battery applications, the consumption of lithium-ion batteries has also increased significantly, and the demand for battery-related raw materials such as nickel, cobalt, manganese, lithium and graphite has also increased significantly. This trend is expected to lead to a serious shortage of these raw materials in the future. In addition, the indiscriminate incineration or landfill of waste batteries will lead to large amounts of greenhouse gas emissions and soil and water pollution.

[0003] Lithium iron phosphate, a material known for its olivine structure, is considered one of the most promising cathode materials for lithium-ion batteries. Lithium iron phosphate is cost-effective, durable, thermally stable, non-toxic, has reduced fire risk, and excellent electrochemical performance.

[0004] Although lithium iron phosphate batteries are recognized as environmentally friendly "green" batteries, improper handling can also cause major safety hazards such as explosions and fires. This not only threatens human health and property safety, but also harms the natural environment. In addition, low-temperature polycrystalline batteries contain harmful components such as electrolytes, plastics and phosphorus, which further emphasizes the importance of correct handling and recycling processes. As a potential resource, the recycling of waste lithium-ion batteries can save more than 20% of the total cost of lithium-ion batteries, and at the same time plays an important role in reducing environmental pressure and preventing battery environmental pollution.

[0005] At present, traditional recycling methods include pyrometallurgy, hydrometallurgy and direct recycling. However, these traditional recycling methods have the disadvantages of complicated recycling steps and low recovery rate. Summary of the invention

[0006] The present invention discloses a method for recovering metals in waste lithium iron phosphate batteries based on advanced oxidation and its application, aiming to provide a new method for the field of lithium battery recycling by exploring the field of lithium battery recycling.

[0007] The present invention adopts the following scheme to achieve the above purpose:

[0008] A method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation, the method comprising the following steps:

[0009] S1. The waste lithium iron phosphate battery is completely discharged and dried in the air, and then the positive electrode material is separated and the positive electrode material is immersed in deionized water to remove the electrolyte;

[0010] S2. The cathode material after removing the electrolyte and the aluminum foil are separated and filtered in water, washed several times with deionized water, dried and ground into powder to obtain cathode material powder; the cathode material powder contains lithium iron phosphate;

[0011] S3. The positive electrode material powder and the oxidant are added to a beaker in a certain proportion and mixed with water, and stirred at room temperature for 20 minutes, thereby releasing the lithium in the lithium iron phosphate into the aqueous solution to obtain a uniform dispersion;

[0012] S4. The uniform dispersion is filtered to separate the remaining iron phosphate / carbon powder solids to obtain a lithium-rich solution;

[0013] S5. The pH value of the lithium-rich solution is adjusted by adding an alkaline solution, and then sodium carbonate is added. The solution is filtered at high temperature and washed several times with hot deionized water to obtain lithium carbonate.

[0014] Preferably, in step S1, the waste lithium iron phosphate battery is a soft-pack lithium iron phosphate battery.

[0015] Preferably, in step S2, the drying condition is drying at 30-80° C. for 2-24 h.

[0016] Preferably, in step S3, the oxidant is one or a combination of peroxymonosulfate PMS, peroxydisulfate PDS, ammonium persulfate, sodium persulfate, and potassium persulfate.

[0017] Preferably, in step S3, the molar concentration of the solution is 1-200 mM, the solid-liquid ratio is 1-1000 g / L, the temperature is 20-80° C., and the solid-liquid ratio of the waste graphite to the ammonium persulfate solution is 1-1000 g / L.

[0018] Preferably, in step S5, the alkaline solution is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 1-10 mol / L.

[0019] Preferably, in step S5, the high temperature is 50-100°C.

[0020] Preferably, it also includes:

[0021] S6, washing the iron phosphate / carbon powder solid with deionized water for multiple times and then drying and recovering it.

[0022] The invention is based on the unique redox property of lithium iron phosphate and uses waste lithium iron phosphate batteries as catalysts to promote the generation of free radicals, thereby realizing the separation and recovery of lithium and iron from waste lithium iron phosphate batteries.

[0023] Compared with the prior art, the present invention can achieve the following technical effects:

[0024] (1) The present invention can realize the efficient recovery of valuable metals in waste lithium iron phosphate batteries, which is not only beneficial to reducing the pollution of waste batteries to the environment, but also can alleviate the problem of lithium resource shortage.

[0025] (2) The leaching rate of lithium in the lithium iron phosphate battery of the present invention can be close to 100%, which reduces many steps compared to the traditional recycling process.

[0026] (3) The method adopted by the present invention does not destroy the structure of iron phosphate and maintains the integrity of the iron phosphate structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 is a graph of lithium leaching rates at different reaction times in Example 1 of the present invention;

[0029] Figure 2 is a graph of lithium leaching rates at different solid-to-liquid ratios of Example 2 of the present invention;

[0030] Figure 3 It is an X-ray diffraction diagram of lithium carbonate recovered after the leaching reaction of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] In this embodiment, a method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation and its application are provided, wherein the lithium leaching solution and lithium carbonate can be obtained according to the following steps:

[0034] (1) The soft-pack lithium iron phosphate battery is completely discharged by an instrument, and then manually disassembled and separated. The positive electrode material is quickly immersed in deionized water to remove impurities such as electrolytes, and the positive electrode material attached to the aluminum foil is manually peeled off. After multiple washing and drying, it is ground into powder using a mortar to obtain positive electrode material powder.

[0035] (2) PMS and positive electrode material powder were added into a beaker at a ratio of 1.15 and mixed with water in a 25°C water bath environment. The mixture was stirred at 200 r / min and leached for 1, 5, 10, 15, 20, 25, 30, and 40 minutes respectively (solid-liquid ratio was 10 g / L).

[0036] (3) The remaining iron phosphate / carbon is separated by filtration to obtain a lithium-rich solution. The sample to be tested is quantitatively analyzed by flame atomic absorption spectrometry to draw a lithium leaching rate diagram. Figure 1 Graph showing lithium leaching rate versus reaction time in this example.

[0037] It can be seen that after 5 minutes, the lithium leaching rate is basically stable and close to 100%. Therefore, this embodiment has the advantages of fast leaching speed and high leaching rate.

[0038] (4) A certain amount of sodium hydroxide is dissolved in water to obtain a 2 mol / L sodium hydroxide aqueous solution, which is added dropwise to the lithium-rich solution to adjust the pH to 8, and then a saturated sodium carbonate solution is added to the lithium-rich solution. The solution is evaporated in a water bath at 95° C. for 1 h, and then filtered to obtain a white solid, which is washed three times with 95° C. deionized water to obtain lithium carbonate.

[0039] (5) The iron phosphate / carbon powder solid is washed with deionized water for multiple times and then dried and recovered.

[0040] The method adopted in this embodiment does not destroy the structure of the iron phosphate, and maintains the integrity of the iron phosphate structure.

[0041] Example 2

[0042] In this embodiment, a method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation and its application are provided, wherein the lithium leaching solution and lithium carbonate can be obtained according to the following steps:

[0043] (1) The soft-pack lithium iron phosphate battery was completely discharged by the instrument, and then manually disassembled and separated. The positive electrode material was quickly immersed in deionized water to remove impurities such as electrolytes, and the positive electrode material attached to the aluminum foil was manually peeled off. After multiple washing and drying, it was ground into powder using a mortar.

[0044] (2) PMS and positive electrode material powder were added into a beaker at a ratio of 0.95 and mixed with water in a 25°C water bath environment, mixed and stirred at 200 r / min, and leached for 20 minutes (solid-liquid ratio was 10, 15, 20, 25, 30 g / L).

[0045] (3) The remaining iron phosphate / carbon is separated by filtration to obtain a lithium-rich solution. The sample to be tested is quantitatively analyzed by flame atomic absorption spectrometry to draw a lithium leaching rate diagram. Figure 2 This is a graph of lithium leaching rates under different solid-to-liquid ratios provided for this embodiment.

[0046] It can be seen that the lithium leaching rates of different solid-liquid ratios are not much different, and all have high lithium leaching rates. Therefore, the operation of this embodiment is relatively simple, the requirements for conditions are not very strict, and it is suitable for industrial applications.

[0047] (4) A certain amount of sodium hydroxide is dissolved in water to obtain a 2 mol / L sodium hydroxide aqueous solution, which is added dropwise to the lithium-rich solution to adjust the pH to 8, and then a saturated sodium carbonate solution is added to the lithium-rich solution. The solution is evaporated in a water bath at 95° C. for 1 h, and then filtered to obtain a white solid, which is washed three times with 95° C. deionized water to obtain lithium carbonate.

[0048] like Figure 3 As shown, by analyzing the relative intensity of the product, it can be proved that lithium carbonate is recovered.

[0049] (5) The iron phosphate / carbon powder solid is washed with deionized water for multiple times and then dried and recovered.

[0050] The method adopted in this embodiment does not destroy the structure of the iron phosphate, and maintains the integrity of the iron phosphate structure.

[0051] The above-mentioned embodiment of the present invention is based on the unique redox characteristics of lithium iron phosphate, and uses waste lithium iron phosphate batteries as catalysts to promote the generation of free radicals, thereby achieving separation and recovery of lithium and iron from waste lithium iron phosphate batteries.

[0052] Compared with the prior art, the present invention can achieve the following technical effects:

[0053] (1) The present invention can realize the efficient recovery of valuable metals in waste lithium iron phosphate batteries, which is not only beneficial to reducing the pollution of waste batteries to the environment, but also can alleviate the problem of lithium resource shortage.

[0054] (2) The leaching rate of lithium in the lithium iron phosphate battery of the present invention can be close to 100%, which reduces many steps compared to the traditional recycling process.

[0055] (3) The method adopted by the present invention does not destroy the structure of iron phosphate and maintains the integrity of the iron phosphate structure.

[0056] The above are only preferred embodiments of the present invention, which are used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific embodiments. The protection scope of the present invention is not limited to the above embodiments, and all technical solutions under the concept of the present invention belong to the protection scope of the present invention.

Claims

1. A method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation, characterized in that: The method comprises the following steps: S1. The waste lithium iron phosphate battery is completely discharged and dried in the air, and then the positive electrode material is separated and the positive electrode material is immersed in deionized water to remove the electrolyte; S2. The cathode material after removing the electrolyte and the aluminum foil are separated and filtered in water, washed several times with deionized water, dried and ground into powder to obtain cathode material powder; the cathode material powder contains lithium iron phosphate; S3. The positive electrode material powder and the oxidant are added to a beaker in a certain proportion and mixed with water, and stirred at room temperature for 20 minutes, thereby releasing the lithium in the lithium iron phosphate into the aqueous solution to obtain a uniform dispersion; S4. The uniform dispersion is filtered to separate the remaining iron phosphate / carbon powder solids to obtain a lithium-rich solution; S5. The pH value of the lithium-rich solution is adjusted by adding an alkaline solution, and then sodium carbonate is added. The solution is filtered at high temperature and washed several times with hot deionized water to obtain lithium carbonate.

2. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: In step S1, the waste lithium iron phosphate battery is a soft-pack lithium iron phosphate battery.

3. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: In step S2, the drying condition is drying at 30-80°C for 2-24h.

4. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: In step S3, the oxidant is one or a combination of peroxymonosulfate PMS, peroxydisulfate PDS, ammonium persulfate, sodium persulfate, and potassium persulfate.

5. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: In step S3, the molar concentration of the solution is 1-200 mM, the solid-liquid ratio is 1-1000 g / L, the temperature is 20-80° C., and the solid-liquid ratio of the waste graphite to the ammonium persulfate solution is 1-1000 g / L.

6. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: In step S5, the alkaline solution is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 1-10 mol / L.

7. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: In step S5, the high temperature is 50-100°C.

8. The method for recovering metals from waste lithium iron phosphate batteries based on advanced oxidation according to claim 1, characterized in that: Also includes: S6, washing the iron phosphate / carbon powder solid with deionized water for multiple times and then drying and recovering it.

9. Application of the method for recovering metals from waste lithium iron phosphate batteries by advanced oxidation as described in any one of claims 1 to 8.

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